help on upgrade from 10.20 to 11i v1 fail on change cdrom - HP UX

This is a discussion on help on upgrade from 10.20 to 11i v1 fail on change cdrom - HP UX ; Hi there,
I've met an issue when upgrade a HP-UX box from 10.20(1999?) to 11i
v1(2003) using CDROM fail. It's HP9000 785 C3600 box. The update
procedure is according to http://docs.hp.com/en/5990-7279/ch06s05.html .
The upgrade test was done several times.
1) ...

The upgrade test was done several times.
1) Install 10.20 using Ignity-UX, upgrade to 11iv1 using CDROM, when
promote to change the second CD, can not umount and eject auto. Manual
umount cause bad system calls , core dump. Upgrade exit with error.
2) The same as 1 but success.
3) Fresh install 10.20, upgrade to 11iv1 using CDROM. When promote to
change the second CD, can not umount and eject auto. Manual umount
cause bad system calls , core dump.
4) Same as 3, but can not eject auto. Can manual eject. When insert the
second CD, can not mount, device busy. Upgrade exit with error.

Does any one experience it before? Do I need some patch in 10.20 to
perform the upgrade? Any tricks? Thanks.